Recently , the LIGO-Virgo collaboration reported their first detection of gravitational wave ( GW ) signals from a low mass compact binary merger GW170817 , which is most likely due to a double neutron star ( NS ) merger .
With the GW signals only , the chirp mass of the binary is precisely constrained to 1.188 ^ { +0.004 } _ { -0.002 } ~ { } { M _ { \odot } } , but the mass ratio is loosely constrained in the range 0.4 - 1 , so that a very rough estimation of the individual NS masses ( 1.36 ~ { } { M _ { \odot } } < M _ { 1 } < 2.26 ~ { } { M _ { \odot } } and 0.86 ~ { } { M _ { \odot } } < M _ { 2 } < 1.36 ~ { } { M _ { \odot } } ) was obtained .
Here we propose that if one can constrain the dynamical ejecta mass through performing kilonova modeling of the optical/IR data , by utilizing an empirical relation between the dynamical ejecta mass and the mass ratio of NS binaries , one may place a more stringent constraint on the mass ratio of the system .
For instance , considering that the red ‘ ‘ kilonova ’ ’ component is powered by the dynamical ejecta , we reach a tight constraint on the mass ratio in the range of 0.46 - 0.59 .
Alternatively , if the blue ‘ ‘ kilonova ’ ’ component is powered by the dynamical ejecta , the mass ratio would be constrained in the range of 0.53 - 0.67 .
Overall , such a multi-messenger approach could narrow down the mass ratio of GW170817 system to the range of 0.46 - 0.67 , which gives a more precise estimation of the individual NS mass than pure GW signal analysis , i.e . 1.61 ~ { } { M _ { \odot } } < M _ { 1 } < 2.11 ~ { } { M _ { \odot } } and 0.90 ~ { } { M _ { \odot } } < M _ { 2 } < 1.16 ~ { } { M _ { \odot } } .